let data =
  [("Kim, ChulSoo", 80);
   ("Lee, YoungHee", 90);
   ("Hong, KilDong", 82);
  ]

let pr (name, korean) = printf "%s: %d\n" name korean
let korean (name, kor) = kor
let add m n = m + n

let main =
  List.iter pr data
  let ks = List.map korean data
  let sum = List.fold add 0 ks
  let len = List.length data
  printf "average: %g\n" (double sum / double len)

